Vernakalant for conversion of atrial fibrillation

Vernakalant hydrochloride is a novel anti arrhythmic agent which is atrial selective, blocking the early activating potassium channel and frequency dependent sodium channel. It has a half life of two to three hours. In animal studies, it has been shown to selectively prolong the atrial refractory period without affecting the ventricular refractory period. In a phase 3 trial patients with short duration atrial fibrillation had a 51.7% conversion to sinus rhythm with a median time of eleven minutes. There were 145 patients on vernakalant and 75 patients on placebo in the group with short duration atrial fibrillation. Most common side effects noted were transient dysgeusia and sneezing with vernakalant. Three patients had significant adverse events in the form of hypotension, complete heart block and cardiogenic shock. But the complete heart block and cardiogenic shock occurred after electrical cardioversion as vernakalant infusion had been stopped due to hypotension. In contrast to the good efficacy in atrial fibrillation of short duration, only six of the seventy six patients (7.9%) patients with long duration atrial fibrillation had conversion with vernakalant. Atrial flutter may occur with vernakalant needing AV nodal blocking drugs for rate control of the ventricular rate. Vernakalant seems to have a lower risk for torsades de pointes than ibutilide, the other drug for conversion of atrial fibrillation.